Integrated damper control system

ABSTRACT

A damper control device may include an appliance control programmed processor for controlling a gas burner, the appliance control programmed processor including a lockout register for storing electronic data information, and a damper control programmed processor for controlling a damper, the damper control programmed processor including a damper request register for storing electronic data information. The damper control programmed processor may be configured for selectively opening or closing the damper responsive to status of the damper request register and controlling status of the lockout register to indicate status of the damper, and the appliance control programmed processor may be configured for controlling status of the damper request register responsive to a call for operation of the gas burner and operating the gas burner only if the lockout register is in an unlock status.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/458,163, filed Apr. 27, 2012, which claims the benefit of U.S.Provisional Application No. 61/481,921, filed May 3, 2011. Each of theapplications is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to gas fired appliances and, more particularly,to an integrated damper control system for use with a gas firedappliance.

BACKGROUND

A typical gas fired appliance, such as a. boiler, includes a gas burnerfor generating heat. For example, with a boiler the burner is used forheating water. The appliance typically includes a draft hood ordiverter. A vent from the draft hood exhausts products of combustionfrom the appliance. The vent may include a flue damper.

The typical known analog damper control system has proven to be a safeand reliable accessory for fuel fired appliances such as water heaters,furnaces, and boilers. For simplicity, the terms “heat system” and“appliance” are a reference to “fuel fired appliance”. A simple heatsystem is defined as a fuel fired appliance that has analog inputs andoutputs for use with a damper system to control the fuel deliverysolenoid valve. A smart heat system is defined as a fuel fired appliancethat does not have analog inputs and outputs for use with a dampercontrol system.

The analog damper control improves the overall efficiency of a simpleheating system by closing the flue when the heat system is idle. Theanalog damper control incorporates a proving circuit that prevents heatactivity of the appliance when the damper gate is not in the openposition. The proving circuit in simplistic terms may include apositioning cam or lever attached to a mechanical switch that wouldelectrically connect or disconnect the heat control signal to the “fueldelivery” solenoid valve in relationship to the damper gate position. Aheat call by the appliance would initiate the damper control to open thedamper gate. When the damper gate is in the open position, the provingswitch will be in the closed position to allow current flow from theappliance to the “fuel delivery” solenoid valve. The proving circuit isa safety switch that would prevent release and firing of fossil fuelwhen the damper is not fully open. A typical damper control system isshown in the diagram of FIG. 1.

More recently, fuel fired appliances have become more complex in design.Introduction of new technology has evolved the simple heat system to amodern smart heat system. Many of the smart heat systems do not haveprovisions for the simple analog damper control. Analog control signalshave been replaced by a serial network interface to transfer data fromthe smart heat system to accessory components such as a damper controlsystem.

One known method that can be used to implement an integrated dampercontrol with a smart heat system is to operate the damper as a heatanticipator. Data that is transferred between the smart heat system andaccessory component could include; set point, temperature, heat activitydata, remote set point, and operating differential. The integrateddamper control reads data from the smart heat system through the serialinterface to determine when to open or close the damper gate. Theoperating temperature, set point and differential will be used tocalculate the operating point or anticipated heat turn on temperature.The anticipated value will predict when heating will occur. The heatactivity or “heating status” of the smart heat system will also bemonitored. When the temperature is close to the anticipated value, theintegrated damper control will send a. low set point data instruction tothe smart heat system to suspend any heat call activity while the damperis transitioning to the open. position. Once the damper has verified thedamper gate is open, the original set point will be transmitted to thesmart heat system to allow for heating to occur. In the event the smartheat system activates the fuel solenoid valve while the damper isclosed, the integrated damper control will momentarily suppress theoperating set point of the smart heat system through the serialinterface to deactivate the heat call. The integrated damper will openthe damper gate and then restore the smart heat system's set point toallow the heat call to commence. The “heating status” register will bemonitored during the heat call to determine when the heat call has beensatisfied. Once the heat call terminates, the damper will be closed.

There are issues with the heat anticipation method such that it ispossible for the smart heat system to activate the fuel deliverysolenoid while the damper gate is in the closed position, which is notpermitted by the safety standards covering fuel fired appliances.

This application is directed to improvements in damper control systems.

SUMMARY

As disclosed herein, an integrated damper control system interfaces adamper control to an appliance control through a network interface.

There is disclosed in accordance with one aspect of the invention adamper control system for use with a gas fired appliance including a gasburner, a flue and a damper for selectively opening the flue. The dampercontrol system comprises an appliance control including a programmedprocessor for controlling the gas burner and a communication interfacedevice. A damper control comprises a programmed processor forcontrolling the damper and a communication interface device forcommunication with the appliance control communication interface device.The damper control programmed processor is programmed to selectivelyopen or close the damper responsive to status of a damper requestregister and to control status of a lockout register to indicate statusof the damper. The appliance control programmed processor is programmedto control status of the damper request register responsive to a callfor operation of the gas burner and to operate the gas burner only ifthe lockout register is set to unlock.

It is a feature that the communication interface devices comprise UARTcircuits to implement the serial interface.

It is another feature that the communication interface devices maycomprise wireless devices.

It is a further feature of the invention that the appliance controlprogrammed processor waits for the lockout register to be set to unlockafter a call for operation of the gas burner.

It is still another feature that the appliance control programmedprocessor writes an open status to the damper request registerresponsive to a call for operation of the gas burner and writes a closestatus to the damper request register responsive to termination of acall for operation of the gas burner.

It is still another feature that the damper control programmed processorsets the lockout register to lock responsive to the damper beingcommanded to close and sets the lockout register to unlock responsive tothe damper being open. The damper control programmed processor mayverify the status of the lockout register before closing the damper.

It is yet another feature that the damper control programmed processorterminates the call for operation of the gas burner in the absence of arequest to open the damper after the call for operation of the gasburner. The damper control programmed processor may lower a temperatureset point of the appliance control programmed processor to effectivelyterminate the call for operation of the gas burner.

It is still a further feature that the damper control programmedprocessor is programmed to open the damper responsive to a hightemperature condition indicated in the appliance control programmedprocessor.

There is also disclosed in accordance with another aspect of theinvention a method of controlling a damper used with a gas firedappliance including a gas burner and a flue, the damper for selectivelyopening the flue, the method comprising providing an appliance controlprogrammed processor for controlling the gas burner; providing a dampercontrol programmed processor for controlling the damper; providingcommunications between the appliance control programmed processor andthe damper control programmed processor; and the damper controlprogrammed processor selectively opening or closing the damperresponsive to status of a damper request register and controlling statusof a lockout register to indicate status of the damper, and theappliance control programmed processor controlling status of the damperrequest register responsive to a call for operation of the gas burnerand operating the gas burner only if the lockout register is in anunlock status.

Other features and advantages will be apparent from a review of theentire specification, including the appended claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a prior art analog vent proving system;

FIG. 2 is a perspective view of a damper control system in accordancewith the invention mounted to a gas fired appliance;

FIG. 3 is a block diagram of the damper control system of FIG. 2;

FIG. 4 is a flow diagram illustrating a program implemented in the heatsystem microprocessor of FIG. 3; and

FIG. 5 is a flow diagram illustrating a program implemented in thedamper control microprocessor of FIG. 3.

DETAILED DESCRIPTION

The integrated damper control system disclosed herein identifiesfunctions and methods to interface a damper control to an appliancecontrol, such as a smart heat system, through a serial networkinterface.

The integrated damper control system performs the same basic function asan analog damper control system. However, the proving circuit isisolated from the smart heat system and not directly connected to thefuel delivery solenoid. The damper gate position is monitored by theintegrated damper control by use of a motorized cam and positionswitches that indicate to a microprocessor the open or closed state ofthe gate. The serial interface of the smart heat system is used totransmit and receive data to the integrated damper control.

A safe and reliable method to operate an integrated damper control witha smart heat system control incorporates a direct register control thatpermits or prevents the fuel delivery solenoid activity in relation tothe damper gate position.

The direct register control method requires two control registers thatare internal to the smart heat system. One control register defined as“damper request” will be written by the smart heat system to indicate arequest to open and to indicate a request to close the damper. The“damper request” register will be monitored by the integrated dampercontrol once per second. The second control register defined as“lockout” can only be written to by the integrated damper control. The“lockout” register can only be read by the smart heat system todetermine if heating is permitted or prohibited.

Referring to FIG. 2, a gas fired appliance 10 of conventionalconstruction is illustrated. The gas fired appliance 10 may comprise,for example, a boiler. For simplicity herein, the gas fired appliance 10will be referred to as a boiler, it being understood that the inventionis not limited to use in connection with a boiler. The boiler 10includes a flue 12 and a flue damper 16 connected to a draft hood 14.The draft hood 14 is in turn connected to a vent pipe or stack 18through a wall opening 20 to exhaust products of combustion from theboiler 10 to the exterior of the building. Again, for simplicity herein,the ducts and/or pipes used in venting from the boiler 10 will bereferred to as a “vent”. The internal pipe of the boiler 10 which isattached to the flue damper control shall be referred to as a “flue”.The present invention is not directed to any particular gas firedappliance or configuration of the venting system. In accordance with theinvention, a damper control 22 is operatively associated with the fluedamper 16.

The flue damper 16 may be of conventional construction such asillustrated in U.S. Publication No. 2011/0114034, owned by the assigneeof the present application, the specification of which is incorporatedby reference herein. The flue damper 16 includes a gate controlled by amotor, not shown herein, to selectively open or close the flue 12, as isconventional.

Referring to FIG. 3, the damper control 22 communicates with anappliance control 30 to form a damper control system 24. The appliancecontrol 30 in one form comprises a smart heat system and comprises aprogrammed processor, such as the microprocessor 34 and associatedmemory, for controlling a solenoid valve 36 associated with a gasburner. A UART communication device 38 is operatively connected to themicroprocessor 34. As will be apparent, the appliance control 30 mayinclude a thermostat and the like and is programmed to control theoverall operation of the gas fired appliance 10. Typically, themicroprocessor 34 uses a programmable set point and thermostat. If thetemperature is above the set point, then the solenoid valve 36 is off.If the measured temperature is below the set point, then themicroprocessor 34 turns on the solenoid valve 36 to ignite the gasburner. As will be apparent, there may be other associated devicesaccording to the design of the particular gas fired appliance. Thisapplication is not directed to those features of the appliance control,but rather the interaction with the damper control 22, as describedbelow.

The damper control 22 comprises a programmed processor, such as amicroprocessor 40 and associated memory operatively connected to aproving switch 42. The proving switch 42 senses position of a positioncam 44. The position cam 44 is associated with the flue damper gate 16and is rotational therewith. The proving switch 42 is selectively openedor closed dependent on whether the flue damper 16 is closed or open, asis known. The microprocessor 40 is in operative communication with aUART communication device 46 and communicates via a serial interface 48to the appliance control UART 38. The serial interface may use any formof communication, such as RS-232, RS-485, IRDA, I2C or SPI. Thecommunication may also use a wireless network or other data exchangemethods, as necessary or desired.

Referring to FIG. 4, a flow diagram illustrates a smart heat programimplemented in the appliance control microprocessor 34 of FIG. 3. Asnoted above, the appliance control 30 performs various other functionsnot described in detail herein. The program begins at a block 50 whichmonitors a heat status register. The heat status register indicateswhether there is a call for heat such as based on the need to satisfy atemperature demand, or the like. A decision block 52 determines whetheror not there is a call for heat. If not, the program moves back to theblock 50 until there is a call for heat. Once there is a call for heat,then a decision block 54 determines whether or not a lockout register isset to “unlock”. The lockout register is controlled by the dampercontrol microprocessor 40 over the serial interface 48. If not, then ablock 56 writes an open status to the damper request register. Theprogram waits until the lockout register is changed to unlock. Once thisoccurs, then heat is turned on at a block 58 as by providing a heatsignal to the solenoid valve 36 to ignite the gas burner.

Once the heat is on, then the program monitors the heat status registerat a block 60 and a block 62 determines if there is still a call forheat. If so, then the program loops back to the block 60. Once the callfor heat has been removed, then the program writes a close status to thedamper request register at a block 64 and the heat signal to thesolenoid valve 36 is turned off at a block 66. The program then returnsto the block 50.

Referring to FIG. 5, a flow diagram illustrates operation of a programimplemented in the damper control microprocessor 40 of FIG. 3. Theprogram continually monitors the damper request register at a decisionblock 70. Once the damper request register has been changed to open,then a block 72 opens the damper by appropriately energizing the dampermotor. A decision block 74 determines if the damper is open, asindicated by the status of the proving switch 42.

If not, then the program loops back to the block 72. Once the damper isopen, then the program sets the lockout register to unlock at a block76.

A decision block 78 monitors to see if there is any status change suchas if the heat call is terminated. This can be done by reading thedamper request register and/or monitoring the heat status register. Ifthere is no status change, then the program loops back. If so, then theprogram sets the lockout register to lock at a block 80. A block 82verifies that the lockout register has been changed to lock. Thereafter,the damper is closed at a block 84. The program loops back to the block70.

Optionally, an alternative routine may be used to provide forredundancy. If there is no damper request, as determined at the decisionblock 70, then a decision block 80 may determine if there is a call forheat. If so, then the system waits at a block 88 and then determines ata decision block 90 if the damper request register has changed. If so,then the program proceeds to the block 72, discussed above. If not, thenthe program lowers the heat set point at a block 92, opens the damper ata block 94, and subsequently restores the heat step point at a block 96.The program then advances to the block 76.

As is apparent, the appliance control microprocessor 34 and the dampercontrol microprocessor 40 communicate over the serial interface 48 as byreading appropriate registers of one another to provide an integratedsystem.

Overall operation of the gas fired appliance 10 is now described. In aheating mode, once the smart heat system appliance control 30 determinesthat heating is required to maintain operating temperature, thefollowing events will take place.

The appliance control 30 reads the lockout register to verify if heatingcan take place. If the lockout register contains the unlock code,heating may commence without delay. The heat status register is set toindicate heating is active. If the lockout register contains the lockcode, heating will be prohibited until the integrated damper control 22writes to this register the unlock code. The smart heat system willwrite to the damper request register the request to open code

The integrated damper control 22 monitors the damper request registeronce per second. In the event the damper request register has therequest to open code, the integrated damper control 22 will open thedamper 16. When the damper gate has been verified it is open, theintegrated damper control 22 sends a write command to the appliancecontrol 30 with the unlock code.

During the heat call, the integrated damper control 22 monitors thesystem heat status register to determine when the heat call hasterminated. The damper request register is also monitored for a requestto close the damper. The integrated damper control 22 sends a writecommand and the lock code to the lockout register immediately after ithas been determined that the heat call has ended by reading the heatstatus register or by a request to close code is present in the damperrequest register.

Once the integrated damper control 22 has issued the lock code to thelockout register, it will be read back from the appliance control 30 toverify it is set prior to closing the damper gate. Once the correctvalue of the lockout register has been verified, the integrated dampercontrol 22 closes the damper and waits for the next call for heat.

The integrated damper control 22 monitors both the damper requestregister and heat status register to ensure a heat call does not occurwhile the damper gate is closed.

As a form of redundancy, if for any reason the appliance control 30activates a heating call without a request to open the damper or if the“lockout” register is set to lock, the integrated damper control 22forces a low set point condition to the appliance control 30 to in orderto terminate the heat call. The integrated damper control 22 opens thedamper gate. Once the damper gate has been verified, the original setpoint is restored to allow the appliance control 30 to operate. Thiswill be considered a recoverable fault condition that will allow theappliance control 30 to operate. As a safety measure, the damper willresume normal operation only if the appliance control 30 disabledheating when the set point was dropped to a minimum value. If the erroroccurs during the next three heat cycles, the fault will be consideredas a non-recoverable failure. A non-recoverable failure will prevent thedamper from closing until power is cycled off to reset the integrateddamper control.

The integrated damper control 22 can provide additional safety featureswhen used with a self-powered appliance. The self-powered fuel firedappliance consists of a standing pilot and thermoelectric generator tocreate electrical energy to operate. The damper gate would have aventilation port to sustain the pilot operation. In the event that theself-powered appliance has been idle for an extended time, it ispossible for the water contained within the heated vessel to exceed thesafe operating temperature. The integrated damper control 22 can monitorthe water temperature by requesting temperature data from the appliancecontrol 30 through the serial interface 48. Once it has been determinedthat the measured water temperature has surpassed the safe operatingpoint the damper will open to reduce the water temperature by means ofconvective ventilation. The damper will remain open until watertemperature drops below the unsafe water temperature.

The present invention has been described with respect to a programsequence of operation and block diagrams. It will be understood thateach step of the sequence and block of the block diagrams can beimplemented by computer program instructions. These program instructionsmay be provided to a processor to produce a machine, such that theinstructions which execute on the processor create means forimplementing the functions specified in the steps and/or blocks. Thecomputer program instructions may be executed by a processor to cause aseries of operational steps to be performed by the processor to producea computer implemented process such that the instructions which executeon the processor provide steps for implementing the functions specified.Accordingly, the description and illustrations support combinations ofmeans for performing a specified function and combinations of steps forperforming the specified functions. It will also be understood that eachblock and combination of blocks can be implemented by special purposehardware-based systems which perform the specified functions or steps,or combinations of special purpose hardware and computer instructions.

It will be appreciated by those skilled in the art that there are manypossible modifications to be made to the specific forms of the featuresand components of the disclosed embodiments while keeping within thespirit of the concepts disclosed herein. Accordingly, no limitations tothe specific forms of the embodiments disclosed herein should be readinto the claims unless expressly recited in the claims. Although a fewembodiments have been described in detail above, other modifications arepossible. For example, the logic flows depicted in the figures do notrequire the particular order shown, or sequential order, to achievedesirable results. Other steps may be provided, or steps may beeliminated, from the described flows, and other components may be addedto, or removed from, the described systems. Other embodiments may bewithin the scope of the following claims.

I claim:
 1. A damper control system, comprising: an appliance control programmed processor for controlling a gas burner, the appliance control programmed processor including a lockout register for storing electronic data information; and a damper control programmed processor for controlling a damper, the damper control programmed processor including a damper request register for storing electronic data information, wherein the damper control programmed processor is configured for selectively opening or closing the damper responsive to status of the damper request register and controlling status of the lockout register to indicate status of the damper, and the appliance control programmed processor is configured for controlling status of the damper request register responsive to a call for operation of the gas burner and operating the gas burner only if the lockout register is in an unlock status.
 2. The damper control system of claim 1, wherein communications between the appliance control programmed processor and the damper control programmed processor are included via UART circuits to implement a serial interface.
 3. The damper control system of claim 1, wherein communications between the appliance control programmed processor and the damper control programmed processor are formed by wireless communications.
 4. The damper control system of claim 1, wherein the appliance control programmed processor waits for the lockout register to be set to unlock after a call for operation of the gas burner.
 5. The damper control system of claim 1, wherein the appliance control programmed processor writes an open status to the damper request register responsive to a call for operation of the gas burner and writes a close status to the damper request register responsive to termination of a call for operation of the gas burner.
 6. The damper control system of claim 1, wherein the damper control programmed processor terminates the call for operation of the gas burner in the absence of a request to open the damper after the call for operation of the gas burner.
 7. The damper control system of claim 6, wherein the damper control programmed processor lowers a temperature set point of the appliance control programmed processor to effectively terminate the call for operation of the gas burner.
 8. The damper control system of claim 1, wherein the damper control programmed processor is programmed to open the damper responsive to a high temperature condition indicated in the appliance control programmed processor.
 9. A damper control system, comprising: an appliance control programmed processor for controlling a gas burner, the appliance control programmed processor including a lockout register for storing electronic data information; and a damper control programmed processor for controlling a damper, the damper control programmed processor including a damper request register for storing electronic data information, wherein the damper control programmed processor is configured for selectively opening or closing the damper responsive to status of the damper request register and controlling status of the lockout register to indicate status of the damper, wherein the appliance control programmed processor is configured for controlling status of the damper request register responsive to a call for operation of the gas burner and operating the gas burner only if the lockout register is in an unlock status, wherein the damper control programmed processor terminates the call for operation of the gas burner in the absence of a request to open the damper after the call for operation of the gas burner, and wherein the damper control programmed processor lowers a temperature set point of the appliance control programmed processor to effectively terminate the call for operation of the gas burner.
 10. The damper control system of claim 9, wherein communications between the appliance control programmed processor and the damper control programmed processor are included via UART circuits to implement a serial interface.
 11. The damper control system of claim 9, wherein communications between the appliance control programmed processor and the damper control programmed processor include wireless communications.
 12. The damper control system of claim 9, wherein the appliance control programmed processor waits for the lockout register to be set to unlock after a call for operation of the gas burner.
 13. The damper control system of claim 9, wherein the appliance control programmed processor writes an open status to the damper request register responsive to a call for operation of the gas burner and writes a close status to the damper request register responsive to termination of a call for operation of the gas burner.
 14. The damper control system of claim 9, wherein the damper control programmed processor is programmed to open the damper responsive to a high temperature condition indicated in the appliance control programmed processor.
 15. A damper control system, comprising: an appliance control programmed processor for controlling a gas burner, the appliance control programmed processor including a lockout register for storing electronic data information; a damper control programmed processor for controlling a damper, the damper control programmed processor including a damper request register for storing electronic data information; and wherein the damper control programmed processor is configured for selectively opening or closing the damper responsive to status of the damper request register and controlling status of the lockout register to indicate status of the damper, wherein the appliance control programmed processor is configured for controlling status of the damper request register responsive to a call for operation of the gas burner and operating the gas burner only if the lockout register is in an unlock status, and wherein the damper control programmed processor is programmed to open the damper responsive to a high temperature condition indicated in the appliance control programmed processor.
 16. The damper control system of claim 15, wherein communications between the appliance control programmed processor and the damper control programmed processor are included via UART circuits to implement a serial interface.
 17. The damper control system of claim 15, wherein communications between the appliance control programmed processor and the damper control programmed processor include wireless communications.
 18. The damper control system of claim 15, wherein the appliance control programmed processor waits for the lockout register to be set to unlock after a call for operation of the gas burner.
 19. The damper control system of claim 15, wherein the appliance control programmed processor writes an open status to the damper request register responsive to a call for operation of the gas burner and writes a close status to the damper request register responsive to termination of a call for operation of the gas burner.
 20. The damper control system of claim 15, wherein the damper control programmed processor terminates the call for operation of the gas burner in the absence of a request to open the damper after the call for operation of the gas burner, and wherein the damper control programmed processor lowers a temperature set point of the appliance control programmed processor to effectively terminate the call for operation of the gas burner. 